where we use the similar notation as in [1]} so that frame indices are \(\underline{a},\underline{b}=0,\dots ,9\)  and where \(\eta _{\underline{a}\underline{b}}=\mathrm {diag}(-1,1,\dots ,1)\) . Note that space-time indices are \(M,N=0,1,\dots ,9\) . Following
[1]} we also introduce parametrization
of NSNS two form \(B_{MN}\)  as
\(B_{MN}=\frac{1}{2}\eta _{\underline{a}\underline{b}}(e_M^{ \ \underline{a}}\pi _N^{ \ \underline{b}}-e_N^{ \ \underline{a}}\pi _M^{ \ \underline{b}}) \ .\) 
